* Focus on Friday's Yellen speech
* Ascendis Health leads stocks higher (Updates prices, adds stocks)
JOHANNESBURG, Aug 24 - The South African rand weakened on Thursday, weighed down by expectations of lower domestic interest rates and cautious trade ahead of U.S. Federal Reserve chair Janet Yellen's speech at a central bankers' meeting.
Stocks hit a new record high, with Ascendis Health Ltd ASCJ.J leading the gainers after flagging higher full-year earnings. 1513 GMT, the rand ZAR=D3 traded at 13.2100 per dollar, 0.44 percent weaker than its New York close on Wednesday.
South Africa's consumer price inflation retreated to its lowest in nearly two years, data showed on Wednesday, boosting the chances of further interest rate cuts. said investors, anticipating lower interest rates, were starting to look elsewhere for higher yields.
There was also caution ahead of Yellen's speech on Friday at the Jackson Hole Economic Policy Summit in Wyoming. European Central Bank President Mario Draghi will also speak at the conference.
"The Fed's Jackson Hole Economic Policy Symposium starts this evening, but will only affect markets from tomorrow," Rand Merchant Bank economist John Cairns said in a note, adding: "All eyes through the end of the week are on Jackson Hole."
The Johannesburg All-Share index .JALSH ended 0.76 percent higher at 56,588 points, a new record high. The Top-40 index .JTOPI rose 0.74 percent to 50,101 points, also a record high.
Leading the gainers, Ascendis Health Ltd shares soared 14.92 percent to a 4-1/2 week high of 20.95 rand. The company said it expected its full-year headline earnings per share to rise up to 66 percent.
In fixed income, the yield for the benchmark government bond ZAR186= closed flat at 8.585 percent.